arXiv subjects

Rachel Steinitz-Eliyahu

Publications and source records attributed to Rachel Steinitz-Eliyahu.

3 recordsLinked to original sources

arXiv2026

Application of the exact-factorization density-functional perturbation approach to pentacene crystal and monolayer MoS2

Non-adiabatic effects arising from electron-phonon interactions are often neglected within the Born-Oppenheimer (BO) approximation, which assumes that electronic states adjust instantaneously to nuclear motion. The exact factorization (EF) formalism provides a rigorous framework for treating such effects beyond the adiabatic regime and has recently been adapted to density functional theory (DFT) in the harmonic limit. Building on these foundations, we previously introduced an EF-based perturbative scheme, the EF density-functional perturbation theory (EF-DFPT), that enables the computation of phonon-driven non-adiabatic (NA) corrections to Kohn-Sham (KS) electronic states, up to second order in nuclear displacements. Here, we present the first implementation and application of EF-DFPT to extended periodic materials, focusing on its impact on experimentally relevant observables. Using the pentacene molecular crystal and monolayer MoS2 as representative soft- and stiff-mode systems, respectively, we demonstrate how NA electron-phonon interactions modify the static dielectric response. We show that these modifications originate from the combined effect of NA phonon-dressed electronic wavefunctions and second-order NA energy renormalizations. The resulting behavior is strongly material dependent: NA effects are negligible in monolayer MoS2, whereas in pentacene they lead to pronounced long-range screening effects associated with soft vibrational modes and enhanced electron-phonon coupling.

cond-mat.mtrl-sci↗

arXiv2025

Non-adiabaticity from first principles: the exact-factorization approach for solids

The thorough treatment of electron-lattice interactions from first principles is one of the main goals in condensed matter physics. While the commonly applied adiabatic Born-Oppenheimer approximation is sufficient for describing many physical phenomena, it is limited in its ability to capture meaningful features originating from non-adiabatic coupling effects. The exact factorization method, starting from the full Hamiltonian of electrons and nuclei, provides a way to systematically account for non-adiabatic effects. This formalism was recently developed into an ab initio density functional theory framework. Within this framework we here develop a perturbative approach to the electronic states in solid state materials. We derive exact-factorization-based perturbations of the Kohn-Sham states up to second order in the nuclear displacements. These non-adiabatic features in the calculated energy and wavefunction corrections are expressed in terms of readily available density functional perturbation theory components.

cond-mat.mtrl-sci↗

arXiv2022

Mixed excitonic nature in water-oxidized BiVO$_4$ surfaces with defects

BiVO$_4$ is a promising photocatalyst for efficient water oxidation, with surface reactivity determined by the structure of active catalytic sites. Surface oxidation in the presence of oxygen vacancies induces electron localization, suggesting an atomistic route to improve the charge transfer efficiency within the catalytic cycle. In this work, we study the effect of oxygen vacancies on the electronic and optical properties at BiVO$_4$ surfaces upon water oxidation. We use density functional theory and many-body perturbation theory to explore the change in the electronic and quasiparticle energy levels and to evaluate the electron-hole coupling as a function of the underlying structure. We show that while the presence of defects alters the atomic structure and largely modifies the wavefunction nature, leading to defect-localized states at the quasipatricle gap region, the optical excitations remain largely unchanged due to substantial hybridization of defect and non-defect electron-hole transitions. Our findings suggest that defect-induced surface oxidation supports improved electron transport, both through bound and tunable electronic states and via a mixed nature of the optical transitions, expected to reduce electron-hole defect trapping.

cond-mat.mtrl-sci↗